Paint cans conventionally have a channel that matingly receives a rib on the lid. The lid is removable and the construction is such as to provide an air tight seal necessary to preserve the content of the container. During use the inner peripheral edge of the rim is used to scrape off excess paint from the paint brush with the result paint often gets into the channel. Also when pouring paint from the container some paint remains in the channel and it is well known to many as to what can happen when a paint can lid is tapped into place closing the container while there is still paint in the channel.
It is difficult to remove the paint from the channel and a common practice of painters is to drive a nail through the bottom of the channel at different locations so as to form drain holes whereby the liquid in the channel will drain back into the container or be forced into the container when the lid is put back on the paint pail. This is a hap hazard arrangement which often damages the rather delicately and integrally formed walls of the channel that provide an air tight seal with the rib on the lid.